Summary form only given. Low aspect ratio spherical tori have manytheoretical advantages over the traditional large aspect ratio tokamaks,In particular, one is exploring different plasma regimes, and with thelow aspect ratio one has high P with absolute magnetic well and highbootstrap fraction. Because of the high-qψ, one shouldhave reduced disruptive behavior. Concerning transport in sphericaltori, microinstabilities should be reduced because of geometric and flowshear properties. Two proof-of-principle spherical tori online are NISTat Princeton and MAST at Culham. These high β plasmas have ωpeωoe so that neither the O-mode orthe X-mode are appropriate for heating or driving non-inductive currentsin the plasma core. However, under certain conditions, an externallylaunched O- or X-mode will undergo efficient mode conversion to electronBernstein wave (EBW). We examine O-X-EWB conversion for frequenciesunder consideration for operation in MAST: f=60 GHz and f=28 GHz, and inparticular, we estimate the absorbed power at both these frequencies aswell as any constraints on required beam alignment andpolarization
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